Wednesday, March 9, 2011

Lightweight Web Services

There has been growing interest in a group of protocols, namely HTTP, REST, OAuth, and JSON, and how they can support web services. REST and JSON, have been around for a while, but one of the puzzling problems was how to handle authentication in REST especially for non-browser based clients using HTTP. So far the only options have been BASIC authentication or SSL/TLS mutual authentication. So far, neither of which have been adequate (but that's a whole other blog post). However, more recently OAuth2 emerged, and offers some possibilities - especially for access to user controlled resources.

Another reason for interest in these protocols has been the emergence of cloud services and smart phones. Instead of using traditional web services such as WS-*, cloud service providers are opting for lighter weight, more quick to implement approaches that focus on basic HTTP. Smart phones with increasingly popular 'app stores' and their obvious need to be lightweight also figure heavily in this surge in interest OAuth, REST, and JSON. It occurs to me that the common theme here is a drive towards something I'll call "lightweight web services".

Pragmatic cloud proponents argue that WS-* and other specifications like SAML, ID-WSF and so on have all become bloated and unworkable. They are just too much for application developers to handle. Why not get 'lightweight' and use specifications like the PortableContacts spec to transfer personal information? Traditionalists argue about security, privacy and other important aspects. In contrast, lightweight web services focus on transport layer security to do most of its work.

Are proponents trading off security, inter-operability, and flexibility for one-shot-at-a-time lightweight services? Let's take a look at the key technologies/standards that comprise lightweight web services so far and talk about some of the challenges/drivers going forwards...

HTTP is the foundation upon which Lightweight Web Services are built. The founding protocol on the web, HTTP is getting a new look as new application clients begin using HTTP rather than just browsers. Driven by social media and the emergence of smart-phone applications and cloud services, HTTP is now the foundation protocol upon which both browsers and application clients are accessing resources and services on the web.

REST has been around for a while. Before it was popular, early web systems used REST like calls in the 90s (before it was called REST). REST creates simple, easy to document APIs that are more URL centric that seem to be more friendly to developers. The emergence of social network APIs (e.g. the Facebook Graph APIs) are good examples. It seems that many developers would rather trade discovery based code generation (e.g. facilitated by WSDLs) for simple-to-read web site documentation and manual code writing against a simple REST API.

JSON or JavaScript Object Notation is the new XML. It enables simple results from REST based service calls to be returned to clients. From wikipedia...
"It is derived from the JavaScript programming language for representing simple data structures and associative arrays, called objects. Despite its relationship to JavaScript, it is language-independent, with parsers available for most programming languages."
OAuth2, originally a method of delegating authorization to access web services (typically used in social media), OAuth2 is quickly becoming a badly needed authentication/authorization services for non-browser web application clients. While browser authentication had quickly migrated from BASIC Authentication (defined by RFC 2617) to Forms based authentication supported by cookies, OAuth provides new browser-less client applications a needed method to authenticate to web services using the HTTP Authorization header.

Shaping Lightweight Web Services
Lightweight web services have come on so strong proponents have generated "need it yesterday" demand for features that aren't yet defined or standardized. Some features are critical and while others are debatable. At present, there is still no standardized authentication token suitable for non-browser web service clients; no signing and/or encryption of content (other than TLS); no concept of message handling and much more. Are we rushing to re-invent here because of the design to have a single tool for all jobs? Or is this just a case of building out REST services to a supportable, secure level of some sort?

The lightweight web has so far been a loosely associated set of technologies with some interesting design patterns in common. As enterprises are quickly joining the community, it seems important that lightweight web services gain a more formal status with discussion in a new working group.

I invite everyone to help further define what are Lightweight Web Services and to help define a WG to help steer the development of relevant IETF and non-IETF standards that make up lightweight web services.

1 comment:

Steven Carlton said...

Awesome article indeed ! I hope I'll be a good web developer soon Web Services does Magnificent web services too. Anyways thanks for sharing!

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